As if President Barack Obama’s political machine hasn’t left them battered and bruised enough, Republicans are fretting that it could help Democrats win the House next year.

The president’s deep-pocketed political arm, Organizing for Action, can’t by law spend most of its money on elections, and officials insist it won’t play directly in the 2014 midterm. But Republicans aren’t buying it: They’re convinced OFA will find other, indirect ways to help Democrats capture the House and allow Obama to finish his presidency unchecked by Congress.

When the group launched a series of Internet ads in February pressing Congress to pass a gun control bill, the target list looked like a who’s who of vulnerable House Republicans. Even Obama’s deputy campaign manager, Stephanie Cutter, said recently that OFA “can affect elections even if legally we can’t be involved with them.” After a gun control bill failed in the Senate last week, the group vowed to keep the heat on dissenting members — Republicans and Democrats alike.

While OFA’s plans to solicit big-dollar donations to advance Obama’s agenda have made headlines, its potential role in 2014 has drawn less notice. But Republicans are paying attention.

“We’ll take it seriously. The president is hellbent on taking back the House so he will have no resistance in 2015 and 2016,” said Oregon Rep. Greg Walden, the National Republican Congressional Committee chairman. “It’s all about making Nancy Pelosi speaker again.”

Republicans hold a 17-seat advantage, and handicappers say Democrats have little chance of taking the House. But Republicans say OFA could be a powerful weapon for the opposition.

They have several worries. One is that the not-for-profit OFA, through ads that encourage or discourage lawmakers to vote a particular way, will cast Republican incumbents in an unflattering light. They fear the massive voter database that Obama has built since his 2008 run — now in OFA’s hands — will be deployed on House Democrats’ behalf.

Most troubling of all, Republicans say, is that OFA will use its unlimited donations to keep Democratic voters across the country engaged and motivated to go to the polls. During the last midterm election, when the GOP seized control of the House, Republicans benefited from low Democratic turnout.

Republicans — still picking up the pieces from a disastrous 2012 election — say there’s nothing in their arsenal that can match OFA’s power.

OFA has “the potential to play a significant role if they so choose,” said Brian Walsh, a former NRCC political director. “Any time you have someone from the left getting involved in House races, it’s a challenge, particularly if they have the infrastructure of a presidential candidate. It’s something Republicans are going to have to take into consideration.”

Obama allies insist that there’s nothing political about the newly revamped OFA — its intentions, they say, are strictly policy-focused. They say the group won’t run ads that explicitly call for the defeat or election of a candidate, and it won’t air advocacy commercials close to the election. Last week, the group announced that it raised $4.8 million in the first quarter of 2013.

“Organizing for Action is an issue advocacy group, not an electoral one. We mobilize to support the president’s agenda, an agenda a majority of Americans voted for in November,” Jim Messina, Obama’s 2012 campaign manager and OFA’s national chairman, wrote in an email to POLITICO.

“The mission of this organization is to re-balance the power structure away from the special interests that have had undue influence over the policy-making process and give a greater voice to people who are continuing the work of the greatest grassroots movement in history,” he said.

Those promises aren’t doing much to soothe GOP nerves. During a recent meeting with House Republicans, Obama was asked about what role OFA would play in 2014; the president assured them the group had no interest in the election.

And Messina is staying active in the political sphere: He recently huddled with Democratic Congressional Campaign Committee Chairman Steve Israel of New York at Democratic National Committee headquarters, a party official confirmed.

Republicans say they’re taking steps to combat OFA’s presence. The NRCC has begun beefing up its digital department and has created a strategy group focused on better understanding district-by-district data in anticipation of OFA’s involvement. Republicans don’t know exactly what role OFA will play but are operating under the assumption that it could strengthen Democrats’ hand.

OFA officials say the group will focus on ads pressing for action on White House priorities like immigration reform and gun control. In February, the group purchased Internet banner ads asking 16 House Republicans to crack down on firearm sales. It did not go unnoticed that nearly all of the Republicans are on the Cook Political Report’s list of the most vulnerable GOP members in 2014.

OFA officials argue that it makes sense to focus ads on vulnerable Republicans because their districts have large numbers of Democratic voters and they’re more likely to back White House legislation. And OFA isn’t exempting Democrats from its ad campaigns. OFA recently ran online ads encouraging 11 senators to support background checks. One of the senators, Martin Heinrich of New Mexico, was a Democrat.

Republicans say two years of advocacy ads in swing districts could make a difference come November 2014.

“While Organizing for Action has recently attempted to re-brand itself as an advocacy group following the November election, it remains an overtly political operation more concerned with dividing people than accomplishing anything positive,” California Rep. David Valadao, an endangered Republican who was among those featured in the gun control banner ad, wrote in an email.

Then there’s the issue of OFA’s treasure-trove of voter data, collected over the course of two presidential campaigns. As a tax-exempt 501(c)(4) group, OFA can’t donate data to candidates or national campaign committees. But it can sell it to them at fair-market value, said Paul Ryan, an attorney with the Campaign Legal Center, a political legal watchdog group.

Where OFA might have its biggest impact is in keeping Democratic voters motivated to head to the polls in 2014. To have any hope of netting the 17 seats needed to take back the House, Democrats say they need to bring out many of the young and minority voters who turned out in 2012.

Many of those voters didn’t turn out in the 2010 midterms. And without Obama on the ballot, Democrats worry many of them will stay home next year. Keeping those voters engaged, they say, will take two years of pushing, prodding and cajoling.

“If OFA energizes and engages voters across this country, including young people, unmarried women and minority voters, in support of the president’s agenda, our campaigns will make sure those voters know where their Republican member of Congress stands when it comes time to vote,” said Jesse Ferguson, the Democratic Congressional Campaign Committee deputy executive director. “We welcome any education and mobilization campaigns like theirs that keep these critical voters engaged.”

Appearing at a POLITICO-sponsored forum just prior to the January Inauguration, Cutter, the Obama campaign official, argued that OFA had the potential to rally the voters who had handed the president a second term.

“This particular organization, the way it’s organized, legally, we can’t participate in elections,” she said. “That doesn’t mean that the issues we’re organizing around won’t mobilize the American people to vote for things. To vote for that economy we’ve been working toward, to vote for immigration reform … I think we can affect elections even if legally we can’t be involved with them for this particular organization.”

Still, some Republicans are skeptical that OFA will be much of a difference-maker.

Brock McCleary, a former NRCC deputy political director, argued that the Obama political arm was a force in 2008 and 2012 because it had a figure to rally around — the president himself. Without Obama running, he said, the organization’s influence will be diluted in 2014.

“I think it’s in the Republicans’ interests to take it very seriously, but I think there are limitations to what impact it could have without President Obama on the ballot,” McCleary said.

For Democrats to win in 2014, they’ll need to play offense on predominantly Republican turf — in other words, districts where the president’s policies often aren’t very popular. Voters in those areas might not like what OFA is selling.

And by the time the midterms role around, some Republicans argue, it’s a good bet swing district voters will have grown weary of the president and the policies his political arm is promoting.

“Sure, he has a formidable machine,” said Brad Todd, a Republican strategist and a veteran of congressional races. “But I wouldn’t go jump off a bridge or anything because the president’s political operation still exists.”